The invention relates to an antenna for a magnetic resonance device with an antenna conductor structure and capacitors connected thereto.
A diagnostic magnetic resonance device is formed of the assemblies basic field system, gradient system and whole-body high-frequency system, among others. The basic field system serves to make available a strong, static and homogenous magnetic field, typically of 0.1 to 4 T. The gradient system delivers a magnetic field which can be adjusted in the low-frequency region (typically up to 1 kHz) and which has a linearly rising, or respectively, falling characteristic in one or more spatial directions with a typical gradient up to 30 mT/m. The high-frequency system makes available a magnetic field for nuclear spin deflection or displacement. The field oscillates in the high frequency region, given an NMR frequency (42, 45 MHZ/T) that is essentially prescribed by the static basic magnetic field. The whole-body high-frequency system is also potentially utilized to receive the signals of the relaxing nuclear spin. In most magnetic resonance devices, these three assemblies surround a cylindrical patient examination space in a shell-like fashion in the sequence: high-frequency system, gradient system, basic field system. The high-frequency system is therein surrounded by a shielding in order to prevent a high-frequency irradiation to the gradient system. The assemblies are therein constructed essentially in the form of a cylinder cladding.
Since, for the most part, the price of the basic field magnet is determined by the free inner diameter (bore), this should be minimized. On the other hand, along with the free inner diameter of the basic field magnet, the thickness of the shell-like construction of gradient system and high-frequency system determine the diameter of the patient space. The thickness of the gradient system and the high-frequency system should thus be minimized in order to maximize the patient examination space.
French Patent Application No. 2 616 911 teaches a superconductive receiving antenna for magnetic resonance signals. A high-temperature superconductor formed of a copper oxide activated by means of rare earth is arranged in a tube or pipe of electrically non-conductive and thermally insulating material. The still free interior of the tube is penetrated by liquid nitrogen as a coolant. After cooling the antenna conductor, the liquid nitrogen reaches the free atmosphere via a valve.
German OS Application 40 13 111 discloses a superconductive receiving antenna in a bath cooling.
German PS Application 42 18 635 teaches an antenna of a metal-oxidic superconductor material with a capacitor having a layer structure of superconductive layer parts formed of the metal-oxidic superconductor material with an intervening solid dielectric layer.